Fan motor assembly

ABSTRACT

A fan motor assembly includes two or more fans adjoining each other and arranged in line. Each fan includes a motor having an impeller, a frame supporting the motor, a housing defining a passage of air flow, at least one rib supporting and fixing the frame to the housing, a lead wire connecting an external power source and the motor, and a lead wire guide portion from which the lead wire is led out of the fan motor assembly. The fan motor assembly includes a primary fan and at least one additional fan. The lead wire of the additional fan is arranged at a surface of an air inlet side or air outlet side of the primary fan, and the lead wire of the additional fan extends out of the primary fan.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a fan motor assembly, and more particularly relates to a fan motor assembly including two or more fans arranged adjacent to each other.

2. Description of the Related Art

Recently, high-end electrical circuits are installed in electrical devices, and such electrical devices generate considerable heat. The electrical devices are generally equipped with a plurality of fans to actively dissipate the heat.

Also recently, it is preferable that the electrical devices have reduced dimensions, such that the electrical devices are likely to be designed to minimize their dimensions. As a result, the space to house a fan motor assembly is limited as well.

The fan includes a lead wire for supplying electricity thereto. When a plurality of fans are provided in the casing of the electrical device, a lead wire of the fan arranged farther from the power source is wired at the outer periphery of the fan arranged nearer the power source. However, in view of the efficient layout of other components within the electrical device casing, the size of a fan housing has to be reduced in order to secure the space for the lead wire. Generally, upon reducing the size of a housing dimension of the fan, a dimension of the wind channel is reduced as well. Consequently, a size of an impeller of the fan is reduced, which results in degrading the airflow and cooling characteristics of the fan.

SUMMARY OF THE INVENTION

In order to overcome the problems described above, preferred embodiments of the present invention provide a fan motor assembly including a primary fan and at least one additional fan. A lead wire connecting the at least one additional fan and an external power source is wired on a surface of an air inlet side or an air outlet side of the primary fan, and then, is led out of the primary fan.

According to another preferred embodiment of the present invention, each fan includes a flange portion at a position outside of a passage of air flow and is either on an air outlet side or an air inlet side of the fan.

According to another preferred embodiment of the present invention, a lead wire connecting the primary fan and the external power source is led out of the primary fan while being bundled together with the lead wire of the additional fan.

By virtue of the unique configuration described above, it is not necessary to secure a space for wiring the lead wire around the fan motor assembly. Therefore, it is not necessary to reduce the inner dimension of the housing or the outer dimension of the impeller. As a result, the fan motor assembly may be installed in a limited space while maintaining appropriate airflow and cooling characteristics.

In the description of the preferred embodiments of the present invention, words such as upper, lower, left, right, upward, downward, top, and bottom for explaining positional relationships between respective members and directions merely indicate positional relationships and directions in the drawings. Such words do not indicate positional relationships and directions of the members mounted in an actual device.

Other features, elements, processes, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a fan motor assembly according to a first preferred embodiment of the present invention.

FIG. 2 is a perspective view showing an alternative embodiment of the first preferred embodiment of the present invention.

FIG. 3 is a perspective view showing another alternative embodiment of the first preferred embodiment of the present invention.

FIG. 4 is a drawing showing a side view of the alternative embodiment described in FIG. 3.

FIG. 5 is a perspective view showing a fan motor assembly according to a second preferred embodiment of the present invention.

FIG. 6 is a plan view showing a fan motor assembly according to a third preferred embodiment of the present invention.

FIG. 7 is a perspective view showing an alternative embodiment of the third preferred embodiment of the present invention.

FIG. 8A is a drawing showing a wire binding member of a fan motor assembly according to a preferred embodiment of the present invention.

FIG. 8B is a drawing showing a wire binding member of a fan motor assembly according to another preferred embodiment of the present invention.

FIG. 8C is a drawing showing a wire binding member of a fan motor assembly according to another preferred embodiment of the present invention.

FIG. 8D is a drawing showing a wire binding member of a fan motor assembly according to another preferred embodiment of the present invention.

FIG. 9 is a fan motor assembly according to another preferred embodiment of the present invention with imaginary planes.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS First Preferred Embodiment

FIG. 1 is a perspective view showing a fan motor assembly according to the first preferred embodiment of the present invention.

A fan motor assembly 3 includes a primary fan 1 and at least one additional fan 2 which are adjacent to each other and arranged in line within a casing of an electrical device. A configuration of the primary fan 1 is described below, which is similar to that of the at least one additional fan 2. Therefore, a detailed explanation of the at least one additional fan 2 will be omitted in terms of the configuration which is similar to the primary fan 1.

The primary fan 1 preferably includes a motor portion 4 rotatably driven by an external power supply. The motor portion 4 includes a fixing portion which is fixed to a frame portion 6. In addition, a rotor portion of the motor portion 4 includes an impeller 5 having a plurality of blades. The primary fan 1 also includes a housing 7 having a circular inside wall defining a substantially cylindrical bore wherein a passage of airflow is generated by rotation of the impeller. The impeller is arranged within the cylindrical bore such that the impeller is surrounded by the circular inside wall of the housing. The frame portion 6 is supported and fixed to the housing 7 by a plurality of ribs 8. In addition, the primary fan 1 includes a lead wire 9 electrically connected to the motor portion 4 to supply electricity thereto.

The at least one additional fan 2 includes a motor portion 4 a, an impeller 5 a, housing 7 a, a lead wire guide portion 10 a provided on the housing 7 a, frame portion 6 a, and a plurality of ribs 8 a. In addition, the primary fan 1 and the at least one additional fan 2 include flange portions 71, 71 a, 72, and 72 a provided at upper corners of the housings 7 and 7 a. A lead wire guide groove 81 a is provided on one of the ribs 8 a which connects the frame 6 a and the lead wire guide portion 10 a, and the lead wire 9 a of the at least one additional fan 2 is led from the lead wire guide portion 10 a to the exterior of the at least one additional fan 2 via the lead wire guide groove 81 a.

Subsequently, the lead wire 9 a is wired along the bottom side of the flange portion 71 a nearest to the lead wire guide portion 10 a, as shown in FIG. 4, and along the bottom side of flange portion 72 adjoining the flange portion 71 a. Then, the lead wire 9 a is wired along the end surface of a wind tunnel portion at an air outlet side of the housing 7. The bottom surfaces of flange portions 71 a and 72 are arranged lower than the end surface of the air outlet side of the housing 7 and the lead wire guide groove 81 a, such that the lead wire 9 a is retained by wiring the lead wire 9 a along the bottom surfaces of flange portions 71 a and 72 while applying the appropriate tension to the lead wire 9 a. In other words, the lead wire 9 a is latched and held by the flange portions 71 a and 72. In this preferred embodiment of the present invention, the lead wire is retained by the flange portions 71 a and 72, but the lead wire may be retained by another member. For example, the lead wires 9 and 9 a may be retained by a convex portion which is formed on the housing of the fan. The end surface of the air outlet side of the housing 7 to which the lead wire 9 a is wired may be arranged lower than the other end surface of the housing 7 such that the lead wire 9 a does not protrude upwardly from the end surface of the housing 7.

The lead wire 9 of the primary fan 1 is led to a lead wire guide portion 10 provided on the housing 7 through a lead wire guide groove 81 provided on one of the ribs 8 connecting the lead wire guide portion 10 and the frame portion 6. The lead wire 9 is bundled together with the lead wire 9 a near the lead wire guide portion 10, and then is led to the exterior of the fan 1. The lead wires 9 and 9 a led out of the fan 1 are bound together by a binding member 12 at the exterior of the housing 7, as shown in FIG. 8A, such that the lead wires 9 and 9 a are fixed without being retractable into the housing 7. The binding member binding the lead wires 9 and 9 a together is not limited to the binding band as shown in FIG. 1. Any suitable binding member, such as a heat shrinkable tube 12′ as shown in FIGS. 8B and 8C, may be used depending on the configuration of the fan motor assembly 3.

Upon wiring the lead wire 9 a of the at least one additional fan 2 to the end surface of the housing 7 of the primary fan 1 at the air outlet side, the lead wire 9 a is arranged at the outer peripheral portion of the passage of airflow of the fan 1. This, however, does not substantially affect the static pressure and the air specifications of the fan. Therefore, predetermined air specifications and static pressure of the fan may be maintained. By using a lead wire which is slim and thin, it is possible to minimize the peripheral portion of the air passage where the lead wire is arranged, if this is desirable. The position where the lead wires 9 and 9 a are led out of the fan motor assembly may be varied depending on the design of the electrical device.

In other words, lead wire 9 and 9 a are arranged between imaginary tangential planes 100 and 101 (see FIG. 9) which are tangential to both of the cylindrical bores of the primary fan and the additional fan and sandwich both of the cylindrical bores therebetween. The lead wires of the primary fan and the additional fan may be bound together at a position which is between the two imaginary tangential planes radially outside of the cylindrical bore of the primary fan and is not placed between an imaginary first sectional plane 102 which connects two tangential points 104 a and 104 b of the cylindrical bore of the primary fan and an imaginary second sectional plane 103 which connects two tangential points 104 c and 104 d of the cylindrical bore of the additional fan.

FIG. 2 is a perspective view showing an alternative embodiment of the first preferred embodiment of the present invention. In this preferred embodiment of the present invention, lead wire grooves 82 and 82 a along the wind tunnel of the corresponding fans are arranged on the air outlet sides of the flange portions 71 and 71 a provided on the housings 7 and 7 a, respectively. The lead wire 9 a of the at least one additional fan 2 is wired along the outer peripheral portion of the air outlet side of the primary fan 1, and then, the lead wire 9 a is bundled together with the lead wire 9 near the lead wire guide portion 10. The lead wires 9 and 9 a bundled together are wired along the lead wire groove 82 and are led from the additional lead wire guide portion 101, including a holding hook 11, provided on the outer side surface of the housing 7 to the exterior of the fan motor assembly. In this preferred embodiment of the present invention, the lead wires 9 and 9 a may be bound together by a heat shrinkable tube 12′ as shown in FIG. 8C, or the binding band 12 as shown in FIG. 8D.

FIG. 3 shows another alternative embodiment of the first preferred embodiment of the present invention. In this preferred embodiment of the present invention, the housing 7 of the primary fan 1 is formed integrally with the housing 7 a of the at least one additional fan 2 to define a single, unitary housing 7. By virtue of this configuration, installation of the fan motor assembly into the electrical device may be simplified.

In the aforementioned preferred embodiments of the present invention, two fans are adjacent to each other and arranged in line. However, the number of the fans may be other than two. For example, three or four fans may be arranged in line and their lead wires may be wired in accordance with the preferred embodiments of the present invention.

Only the reference numerals necessary for explanatory purposes are shown in FIGS. 2, 3, and 4. The configurations and functions of other members are preferably substantially the same as those already described in the first preferred embodiment of the present invention shown in FIG. 1, such that detailed descriptions of those members are omitted.

Second Preferred Embodiment

FIG. 5 is a perspective view showing a fan motor assembly according to the second preferred embodiment of the present invention. In FIG. 5, each member having substantially the same function as the counterpart of the first preferred embodiment shown in FIG. 1 is identified by the same reference numeral.

A fan motor assembly 3 includes a primary fan 1 and at least one additional fan 2 which are adjacent to each other and arranged in line within a casing of an electrical device. A configuration of the primary fan 1 is described below, some of which is similar to that of the at least one additional fan 2. Therefore, detailed explanation of the at least one additional fan 2 will be omitted in terms of the configuration which is similar to the primary fan 1.

The primary fan 1 includes a motor portion 4 rotatably driven by the external power supply. The motor portion 4 includes a fixing portion which is fixed to a frame portion 6. In addition, a rotor portion of the motor portion 4 includes an impeller 5 having a plurality of blades. The primary fan 1 also includes a housing 7 having a circular inside wall defining a substantially cylindrical bore wherein a passage of airflow is generated by rotation of the impeller. The impeller is arranged within the cylindrical bore such that the impeller is surrounded by the circular inside wall of the housing. The frame portion 6 is supported and fixed to the housing 7 by a plurality of ribs 8. In addition, the primary fan 1 includes a lead wire 9 electrically connected to the motor portion 4 to supply electricity thereto.

The lead wire 9 a is led out to the exterior of the frame 6 a of the at least one additional fan 2 in a crosswise direction so that the lead wire 9 a is led to the primary fan 1 adjoining the at least one additional fan 2 while passing the shortest path from the at least one additional fan 2 to the primary fan 1. The lead wire 9 a across the passage of airflow of the at least one additional fan 2 is latched and held to a holding hook 11, defined by a portion of the housing 7 of the primary fan 1 and a portion of the housing 7 a of the at least one additional fan 2, and provided at abounding portion thereof. Subsequently, the lead wire 9 a crosses the passage of airflow of the primary fan 1 and is led to the frame 6 of the primary fan 1. Within the frame 6, the lead wire 9 a is bundled together with the lead wire 9 of the primary fan 1 and led from the lead wire guide portion 10 to the exterior of the primary fan 1 through lead wire guide groove 81 of the primary fan 1.

Alternatively, the lead wires 9 and 9 a bundled together in the frame 6 may cross the passage of airflow of the primary fan 1, and may be led from an additional lead wire guide portion 111 latching and holding the lead wires 9 and 9 a to the exterior of the primary fan 1. The second lead wire guide portion 111 is provided on a side surface of the primary fan 1, opposed to an adjoining side with the at least one additional fan 2. The position where the lead wires 9 and 9 a are led to the exterior of the fan motor assembly may be varied depending on the design of the electrical device. The lead wires 9 and 9 a led out of the primary fan 1 are bound together by a binding member 12 as previously described in the first preferred embodiment, such that the lead wires 9 and 9 a are not retractable into the housing 7.

Third Preferred Embodiment

FIG. 6 is a plan view showing a fan motor assembly according to the third preferred embodiment of the present invention. In FIG. 6, each member having substantially the same function as the counterpart of the first preferred embodiment shown in FIG. 1 is identified by the same reference numeral. Accordingly, identification and detailed explanation of those members will be omitted for simplicity.

A fan motor assembly 3 includes a primary fan 1 and at least one additional fan 2 which are adjacent to each other and arranged in line within a casing of an electrical device. A configuration of the primary fan 1 is described below, some of which is similar to that of the at least one additional fan 2. Therefore, detailed explanation of the at least one additional fan 2 will be omitted in terms of the configuration which is similar to the primary fan 1.

The primary fan 1 includes a motor portion 4 rotatably driven by the external power supply. The motor portion 4 includes a fixing portion which is fixed to a frame portion 6. In addition, a rotor portion of the motor portion 4 includes an impeller 5 having a plurality of blades. The primary fan 1 also includes a housing 7 having a circular inside wall defining a substantially cylindrical bore wherein a passage of airflow is generated by rotation of the impeller. The impeller is arranged within the cylindrical bore such that the impeller is surrounded by the circular inside wall of the housing. The frame portion 6 is supported and fixed to the housing 7 by a plurality of ribs 8. In addition, the primary fan 1 includes a lead wire 9 electrically connected to the motor portion 4 to supply electricity thereto.

In this preferred embodiment of the present invention, the primary fan 1 and the at least one additional fan 2 are adjacent to each other and arranged in line as previously described. The ribs 8 and 8 a are arranged so as to be perpendicular to side surfaces of the housings 7 and 7 a, respectively. In addition, the lead wire groove 81 is provided on one of the ribs 8 extending toward a bounding portion of the housing 7 and the housing 7 a. Similarly, the lead wire groove 81 a is provided on one of the ribs 8 a extending toward the bounding portion.

The lead wire 9 a of the at least one additional fan 2 is led out of the frame 6 a of the housing 7 a to the lead wire guide groove 81 a, and then extends to the primary fan 1 without being led outside of the at least one additional fan 2. At the bounding portion of the primary fan 1 and the at least one additional fan 2, the lead wire 9 a is latched and firmly held by the holding hook 11. Then, the lead wire 9 a is led to the inside of the frame 6 of the primary fan 1 through the lead wire guide groove 81 of the primary fan 1 and is bundled together with the lead wire 9 of the primary fan 1. Then, the lead wires 9 and 9 a are led to the exterior of the primary fan 1 through the lead wire guide groove 81 extending to the opposite side from the bounding portion. The lead wires 9 and 9 a bundled together and led out of the primary fan 1 are bound together by a binding member 12 at the exterior of the primary fan 1. As a result, the lead wires 9 and 9 a are fixed without being retractable into the housing 7.

FIG. 7 is a perspective view showing an alternative embodiment of the third preferred embodiment of the present invention. Each member having substantially the same function as the counterpart of the first preferred embodiment shown in FIG. 1 is identified by the same reference numeral.

In this alternative embodiment of the present invention, the lead wire 9 a of the at least one additional fan 2 is led to the frame 6 of the primary fan 1 adjoining the at least one additional fan 2, and the lead wire 9 a is bundled together with the lead wire 9 of the primary fan 1. Then the lead wires 9 and 9 a are led out of the primary fan 1 as shown in FIG. 6. However, the housing shapes of the primary fan 1 and the at least one additional fan 2 are preferably different from those described in FIG. 6. In this preferred embodiment, the housing 7 of the primary fan 1 includes a plurality of ribs 8 (preferably four) extending radially, and the housing 7 a of the at least one additional fan 2 includes a plurality of ribs 8 a (preferably four) extending radially as well. The lead wire guide grooves 81 and 83 are provided on two of the ribs 8 of the primary fan 1 next to each other. Similar to the primary fan 1, the lead wire guide grooves 81 a and 83 a are provided on two of the ribs 8 a of the at least one additional fan 2 next to each other. In addition, the lead wire groove 82 along the wind tunnel portion of the fan is provided on the flange portion 71 closest to the lead wire guide groove 81 of the primary fan 1. Similarly, the lead wire groove 82 a is provided on the flange portion 71 a closest to the lead wire guide groove 81 a of the at least one additional fan 2.

The lead wire 9 a of the at least one additional fan 2 is led from the frame 6 of the housing 7 a to the lead wire guide groove 81 a. Through the lead wire guide groove 81 a, the lead wire 9 a is led to the lead wire guide groove 82 a arranged on an inner circumferential portion of the flange portion and reaches to the primary fan 1 without being led out of the at least one additional fan 2. Subsequently, the lead wire 9 a is led to the frame 6 through the lead wire guide groove 83. The lead wire 9 a is bundled together with the lead wire 9 within the frame 6, and the lead wires 9 and 9 a are led out of the frame 6 through the lead wire guide groove 81. The lead wires 9 and 9 a are wired along the wind tunnel through lead wire groove 82 and are led out of the primary fan 1 from the lead wire guide portion 111.

It should be understood that the angles between ribs and housings are not limited to those shown in FIGS. 6 and 7. Any suitable angle may be applied to the preferred embodiments of the present invention.

The lead wires 9 and 9 a may be wired in a manner other than those shown in the preferred embodiments of the present invention. The lead wires 9 and 9 a may be wired by a method combining those shown in the preferred embodiments of the present invention. In addition, modifications may be made to the method of wiring the lead wires 9 and 9 a depending on, such as, the design of the electrical device, required air specifications, and characteristics of the fan motor assembly.

While preferred embodiments of the present invention have been described in the foregoing, the present invention is not limited to the preferred embodiments detailed above, in that various modifications are possible. Only selected preferred embodiments have been chosen to illustrate the present invention. To those skilled in the art, however, it will be apparent from the foregoing disclosure that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims. Furthermore, the foregoing description of the preferred embodiments according to the present invention is provided for illustration only, and not for limiting the invention as defined by the appended claims and their equivalents. 

1. A fan motor assembly comprising: a primary fan and at least one additional fan, each of the primary fan and the at least one additional fan including: a motor having an impeller; a frame supporting the motor; a housing defining a passage of air flow generated by the impeller; at least one rib supporting and fixing the frame to the housing; a lead wire arranged to connect the motor to an external power source; and a lead wire guide portion from which the lead wire is led out of the fan; wherein the primary fan and the at least one additional fan are arranged side by side; and the lead wire of the at least one additional fan is arranged on a surface of an air inlet side or an air outlet side of the primary fan, and the lead wire of the at least one additional fan is led to the exterior of the fan motor assembly.
 2. The fan motor assembly as set forth in claim 1, wherein the housing includes a flange portion arranged outside of the passage of air flow; the flange portion is located at an end portion, an air inlet side, or an air outlet side of the housing; and the lead wire of the at least one additional fan is arranged to be latched by the flange portion.
 3. The fan motor assembly as set forth in claim 2, wherein the lead wire of the at least one additional fan is latched by the flange portion of the primary fan and the flange portion of the at least one additional fan, the flange portion of the primary fan and the flange portion of the at least one additional fan adjoining each other.
 4. The fan motor assembly as set forth in claim 2, wherein the lead wire of the at least one additional fan is arranged along an end surface of the housing at the air inlet side or the air outlet side of the primary fan.
 5. The fan motor assembly as set forth in claim 4, wherein a portion of the end surface of the housing on which the lead wire is arranged is recessed relative to the other portions of the end surface of the housing.
 6. The fan motor assembly as set forth in claim 5, wherein the housing of the primary fan is integral with the housing of the at least one additional fan.
 7. The fan motor assembly as set forth in claim 1, further comprising a lead wire guide groove arranged on the at least one rib of each of the primary fan and the at least one additional fan, wherein the lead wire of the at least one additional fan extends from the at least one additional fan to the frame of the primary fan through the lead wire guide groove arranged on the at least one rib of the at least one additional fan, extends past the frame of the primary fan, and is led out of the fan motor assembly through the lead wire guide groove formed on the at least one rib of the primary fan.
 8. The fan motor assembly as set forth in claim 1, wherein the housing includes a flange portion arranged outside of the passage of air flow; the flange portion is located at an end portion, an air inlet side, or an air outlet side of the housing; and the flange portion further includes a lead wire groove through which the lead wire extends from the fan motor assembly.
 9. The fan motor assembly as set forth in claim 1, wherein the lead wire of the at least one additional fan is arranged along an end surface of the air inlet side or the air outlet side of the primary fan, and extends from the fan motor assembly via the lead wire guide portion of the primary fan.
 10. The fan motor assembly as set forth in claim 9, wherein a portion of the end surface of the housing on which the lead wire is arranged is recessed relative to the other portions of the end surface of the housing.
 11. The fan motor assembly as set forth in claim 1, wherein the lead wire of the at least one additional fan is arranged to cross the passage of air flow at an air inlet side or at an air outlet side of the primary fan.
 12. The fan motor assembly as set forth in claim 11, wherein the lead wire of the at least one additional fan extends past the frame of the primary fan.
 13. The fan motor assembly as set forth in claim 1, wherein the lead wire of the at least one additional fan is arranged along an end surface at an air inlet side or an air outlet side of the primary fan, is bundled together with the lead wire of the primary fan at the air inlet side or the air outlet side of the primary fan, and the lead wires of the primary fan and the at least one additional fan extend out of the fan motor assembly from the lead wire guide portion arranged on the housing of the primary fan.
 14. The fan motor assembly as set forth in claim 1, wherein the housing further includes an additional lead wire guide portion which latches and holds the lead wires.
 15. The fan motor assembly as set forth in claim 1, wherein the housing includes a flange portion arranged outside of the passage of air flow; the flange portion is arranged at an end portion, an air inlet side, or an air outlet side of the housing; and the flange portion further includes an additional lead wire guide portion which latches and holds the lead wires.
 16. The fan motor assembly as set forth in claim 1, further including a binding member arranged to bind the lead wires of the primary fan and the at least one additional fan together outside of the primary fan.
 17. The fan motor assembly as set forth in claim 16, wherein the binding member is a binding band or a heat shrinkable tube.
 18. The fan motor assembly as set forth in claim 1, wherein the housing of the primary fan is integral with the housing of the at least one additional fan.
 19. A fan motor assembly including a primary fan and an additional fan, comprising: a housing of the primary fan and a housing of the additional fan arranged laterally adjacent to each other, each of the housings of the primary fan and the additional fan including a circular inside wall defining a cylindrical bore, axes of cylindrical bores of the housings being parallel to each other; a lead wire of the primary fan and a lead wire of an additional fan, first ends of leads wires of the primary fan and the additional fan being connected to the primary fan and the additional fan respectively; and a motor of the primary fan and a motor of the additional fan, motors of the primary fan and the additional fan being accommodated in the cylindrical bores of the primary fan and the additional fan respectively; wherein the lead wires of the primary fan and the additional fan are arranged between imaginary tangential planes which are tangential to both of the first cylindrical bore and the second cylindrical bore and sandwich both of the cylindrical bores therebetween; and the lead wires of the primary fan and the additional fan are bound together at a position which is between the two imaginary tangential planes radially outside of the cylindrical bore of the primary fan and is not placed between an imaginary first sectional plane which connects two tangential points of the cylindrical bore of the primary fan and an imaginary second sectional plane which connects two tangential points of the cylindrical bore of the additional fan.
 20. The fan motor assembly as set forth in claim 19, wherein the lead wire of the additional fan is arranged at least partially along a periphery of the cylindrical bore of the housing of the primary fan.
 21. The fan motor assembly as set forth in claim 19, wherein the primary fan and the additional fan further include a plurality of ribs extending from the motor to the housing; the lead wire of the additional fan is arranged along at least one of the ribs of the primary fan. 